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author | Cyril Bur <cyril.bur@au1.ibm.com> | 2017-11-17 11:29:15 +1100 |
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committer | Stewart Smith <stewart@linux.vnet.ibm.com> | 2017-11-20 20:35:24 -0600 |
commit | 65f9abea8e8cfd7f711a5c54217b5505826ff497 (patch) | |
tree | 73d90554d4c981d13a54105f88df609b2c338e24 /libpore | |
parent | c2e404aedd52da91fdf605e24b9d1ae7894974c5 (diff) | |
download | skiboot-65f9abea8e8cfd7f711a5c54217b5505826ff497.zip skiboot-65f9abea8e8cfd7f711a5c54217b5505826ff497.tar.gz skiboot-65f9abea8e8cfd7f711a5c54217b5505826ff497.tar.bz2 |
libpore: Fix incorrect mtspr instruction generation
>From coverity defect 173758:
CID 173758 (#1 of 1): Unused value (UNUSED_VALUE)
assigned_value: Assigning value from (uint8_t)i_Rs << 21 to
mtsprInstOpcode here, but that stored value is overwritten before it can
be used.
This causes the generated mtspr to always move from register r0 as
opposed to the function parameter i_Rs.
Luckily the only call to getMtsprInstruction is:
getMtsprInstruction( 0, (uint16_t)i_regId );
the first parameter is the register so in an incredible stroke of luck,
the requirement is to generate a mtspr from r0.
Therefore no bug exists today, this is still a fairly important fix
because if anyone uses getMtsprInstruction() with a non zero first
parameter, it will cause them endless headache.
Fixes: CID 173758
Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>
Diffstat (limited to 'libpore')
-rw-r--r-- | libpore/p9_stop_api.C | 10 |
1 files changed, 4 insertions, 6 deletions
diff --git a/libpore/p9_stop_api.C b/libpore/p9_stop_api.C index 26a14bb..33a3bf3 100644 --- a/libpore/p9_stop_api.C +++ b/libpore/p9_stop_api.C @@ -255,12 +255,10 @@ static uint32_t getOrisInstruction( const uint16_t i_Rs, const uint16_t i_Ra, */ static uint32_t getMtsprInstruction( const uint16_t i_Rs, const uint16_t i_Spr ) { - uint32_t mtsprInstOpcode = 0; - uint32_t temp = (( i_Spr & 0x03FF ) << 11); - mtsprInstOpcode = (uint8_t)i_Rs << 21; - mtsprInstOpcode = ( temp & 0x0000F800 ) << 5; - mtsprInstOpcode |= ( temp & 0x001F0000 ) >> 5; - mtsprInstOpcode |= MTSPR_BASE_OPCODE; + uint32_t mtsprInstOpcode = MTSPR_BASE_OPCODE; + uint32_t temp = ((i_Spr & 0x1F) << 5) | ((i_Spr & 0x8F) >> 5); + + mtsprInstOpcode |= ((i_Rs & 0x1F) << 21) | ((temp & 0x03FF) << 11); return SWIZZLE_4_BYTE(mtsprInstOpcode); } |